RAID 5 on El Capitan

[edward_wise]

I have a Akitio enclosure RAID 5 i set up via Terminal following the instructions that have on their site. Since updating to El Capitan, I can no longer see my RAID. In disk utilities I see the separate drives. Their site has this:
"Since the release of OS X El Capitan, the disk utility can no longer be used to create and manage RAID sets. At this time, the only option is to use the Terminal and the diskutil command or purchase and install a 3rd party software like SoftRAID."

But no real instructions on how to fix the issue.

I set it up with OpenZFS, but other than the instructions they provided, have no experience with OpenZFS

[Brendon]

If I read your message correctly, you configured the enclosure in some form of RAID. Then you created ZFS filesystems on that raid set. Now, due to whatever issue you have the raid is no longer visible, and you now see a collection of individual disks. In my opinion, unless you get the raid working again, you're hosed, your data is gone.

Generally speaking from a ZFS point of view we recommend that your enclosure be run in JBOD (Just a Box Of Disks) mode, and allow ZFS redundancy measures to use the raw disks, i.e. configure ZFS filesystems using mirrors, or RAIDZ[2|3].

So, your first action is to attempt to get your RAID setup working again, downgrade your OS if you have to.

Cheers
Brendon

[Haravikk]

If your enclosure supports RAID5 then it should be implemented in hardware, in which case all El Capitan will see is a single big disk, so upgrading the OS shouldn't have affected you at all.

Since you think it has, then it's more likely Akitio provided you with some kind of software RAID that implements RAID5, in which case this is most likely the problem. El Capitan's new security features mean that any kernel extensions that weren't updated to support them may no longer be loading, since software RAID is probably added via a kext this may be the reason for your problems. You can verify this by downgrading to Yosemite; personally I'd recommend installing Yosemite in its own partition to test, but you'll need to find out where the software RAID came from (possibly a disk supplied with the enclosure) and install it, along with OpenZFS. If it works under Yosemite then it's El Capitan that's the problem.

For clarity, AppleRAID (OS X's built in software RAID) does not support RAID5; it only supports concatenation (joining disks "end-to-end"), striping (RAID0) and mirroring (RAID1) plus combinations of the two (RAID10, RAID01 etc.), so changes to Disk Utility definitely aren't the problem. In fact, diskutil hasn't changed at all, only the Disk Utility app (which is just a fancy GUI that seems like it no longer supports RAID).


Anyway, you may want to contact Akitio's support staff, as they may know if the problem is related to El Capitan or not, and can tell you if the RAID5 is provided via hardware or software. If the issue is with El Capitan then at least this way you will know for certain that downgrading should fix it, as it's not really something you want to just try.


If you do have hardware RAID5 then it may perform better than ZFS' RAIDZ, so it may be worth keeping, though it's important to note that RAID5 only protects against disk failure, not data corruption, while RAIDZ protects against both.
If it is in fact software RAID5 then you would be better off using a ZFS RAIDZ as it will provide better protection and performance, since you'll no longer be running both ZFS and software RAID alongside each other.
In both cases migrating to RAIDZ will require you to be able to take a full backup of the volume (so you need to get it working first) so you'll need plenty of space to do-so, but it might be worthwhile in the long run. If you don't have the space then just stick with what works, but it's worth considering in the future.